It is common practice today to open occluded (i.e., blocked) or stenotic (i.e., narrowed) blood vessels by inserting a guide wire and then a catheter carrying a balloon shaped segment and inflating the balloon, which exerts a radial force to press stenosis outward against the wall of the blood vessel. This procedure is called balloon angioplasty. Frequently, an implantable metallic stent will also be used to provide greater radial strength at the stenotic portion of the blood vessel, and to provide longer-term patency.
During the balloon angioplasty procedure and stent placement at the stenotic lesion, there may exist the risk of dislodging fragments of plaque, thrombus (blood clots) and/or other material. These fragments may become dislodged from the stenotic lesion when the balloon segment is inflated. If the lesion involves arterial circulation, then the dislodged particles could flow into smaller vessels in the brain, other organs, or extremities, resulting in disastrous complications. Likewise, if the lesions involve the venous circulation, then the dislodged fragments could flow into the heart and lungs, possibly resulting in the demise of the patient.
Embolic protection devices are typically used to provide protection from such dislodged fragments of plaque and thrombus. These protection devices may consist of a radially expandable segment, such as a balloon, attached near the end of a tube or guidewire. The guidewire with the balloon may be advanced across a stenotic lesion with the balloon in an unexpanded state, and then the balloon may be expanded in an area of the blood vessel past the stenotic lesion or downstream therefrom. When expanded, the balloon can capture and contain dislodged particles. The captured particles may then be removed with various known methods, such as aspiration. When the procedure is completed, the balloon may be deflated and the tube and the deflated balloon may be removed from the patient.
There are disadvantages to such devices. If the targeted blood vessel is tortuous and/or the lesion of the blood vessel to be treated contains a relatively high-grade stenosis, it is often difficult to pass the balloon portion of the catheter through the vessel and into position, even if the balloon portion is deflated. These same problems often arise when the catheter is removed from the patient after the procedure is completed. Even in a deflated position, the crossing profile of the balloon segment may be such that scraping and/or focal dissection of the blood vessel wall may occur as the balloon segment is passed through the diseased portion of the blood vessel, thereby dislodging and releasing embolic material and other particles into the bloodstream. Likewise, the deflated balloon segment of the catheter may often become snagged or caught on the edge of a stent as the balloon segment attempts to pass through such a newly placed stent when the catheter is removed from the patient.
The present invention has been developed in view of the foregoing disadvantages, and to address other deficiencies of the prior art.